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    Re: Use of Sun Sights for Local time,and Lunars for Longitude
    From: Herbert Prinz
    Date: 2002 Oct 29, 04:12 +0000

    I am delighted to hear from George Huxtable that I was able to shed some extra
    light on the subject of lunars.. But first of all, thanks must go to George
    himself, for getting us started in the first place and keeping us motivated to
    think matters through. It is one thing to read old texts and thereby develop a
    rough idea of what lunars are about and how they might have worked. It is yet
    another to put all the bits and pieces of information together and present them
    in a coherent way as George has been doing in his postings to this list for the
    benefit of those who do not have immediate access to the relevant literature or
    even the time to dig through it.
    
    All learning comes from books, but deeper understanding comes from doing. For
    that reason I consider George's contribution invaluable. He outlines procedures
    that actually work with the tools available nowadays. Anybody seriously
    interested in the problem of lunars can actually make the lunar distance
    observation, reduce it and check the result by following the methods George
    presents. He will find that by doing so, he can learn more about the subject
    than he ever could by just reading Cotter or some such text (not to mention the
    cute books on "Longitude" that have become so popular these days).
    
    Most essays on lunars still focus unduly on the problem of clearing the
    distance. (As if it were important whether you eat your french fries with the
    fingers or the fork, when you are hungry.) Indeed, there were over hundred
    "different" methods available to the sailor on the day the authorities in
    charge of the almanac decided not to print the distances anymore. Bruce Stark
    directed our attention towards the fact that the most important aspect of the
    lunar distance method for us in retrospect is not this mere technicality, but a
    proper understanding for the framework in which the navigator operated before
    the chronometer became available.
    
    Participants on this list are certainly aware that Bruce has produced a set of
    tables for reducing the distances that provide an alternative for using a
    calculator as George proposes. There are also a few helpful hints in his
    introduction to these tables that are concerned with the practical side of the
    matter. Bruce laments the fact that no tables of the lunar distances themselves
    are currently available. Although calculator and logarithmic methods for their
    generation from the almanac have been proposed, this creates a hurdle for the
    fainthearted. I am currently looking into a possible remedy.
    
    Herbert Prinz
    
    
    

       
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